1. Technical Field
This invention generally relates to monitoring devices that monitor engineering conditions of pneumatic tires and, more particularly, to an apparatus and method for connecting the power supply to an active, programmable electronic monitoring device mounted on the inside of a pneumatic tire. Specifically, the present invention relates to an apparatus and method for attaching a battery to the components of an active monitoring device after the components are cured into a patch that is attached to the innerliner of a pneumatic tire.
2. Background Information
It is often desired in the art to monitor various engineering conditions of a pneumatic tire. These measurements are preferably taken while the tire is in use on the vehicle without having to remove the tire from the vehicle or specifically position the tire to take the measurement. Numerous types of monitoring devices are known in the art to perform these measurements. One type of monitoring device uses a passive integrated circuit embedded within the body of the tire that is activated by a radio frequency transmission that energizes the circuit by inductive magnetic coupling. Other prior art devices used for monitoring tire conditions include self-powered circuits that are positioned external of the tire, such as at the valve stem. Other active self-powered programmable electronic devices are disclosed in U.S. Pat. Nos. 5,573,610, 5,562,787, and 5,573,611 which are assigned to the assignee of the present application.
Each of the active self-powered programmable electronic devices includes an antenna that is used to transmit the data created by the monitoring device to a data gathering device positioned outside of the tire. One of the problems in the art is to position the antenna such that the data created by the monitoring device is accurately and reliably transmitted to the data gathering device outside of the tire. It is desired to position the antenna as close to the outside of the pneumatic tire as possible so that the transmissions pass through as little of the tire as possible. In the past, the antenna of the monitoring device generally extended into the interior chamber of the tire such that the radio waves had to first pass through the air inside the tire, through the innerliner, through the tire sidewall, and then through the air to the data gathering device. It is desired in the art to provide an antenna for an active, self-powered programmable electronic device that is positioned so that the radio waves do not have to first pass through the inner chamber of the tire before entering the tire sidewall. The bead ring and apex filler of the tire tend to interfere with the radio transmission from the monitoring device. It is thus desired in the art to position the antenna away from the bead ring and apex filler so that the transmission through the tire sidewall is as strong as possible. On the other hand, it is also desirable to position the monitoring device as close to the bead ring as possible because that area of the sidewall is a low flex area that stretches less than the middle portion of the tire sidewall. It is thus desired in the art to ideally locate the antenna and the monitoring device with respect to the tire sidewall.
The monitoring devices known in the art are typically encapsulated with an encapsulation material that provides structural support to the monitoring device so that the device is not destroyed by the forces normally encountered and experienced by a pneumatic tire. Another problem with these electronic monitoring devices is the problem of attaching the encapsulated monitoring device to the tire. The attachment problem is difficult because the forces on the electronic device are significant and numerous. The tires are not only subjected to rotational forces when the vehicle is moving but are also subjected to various impact forces when the tire contacts bumps or surface irregularities. The attachment of the monitoring device to the tire must be strong enough and secure enough to maintain the position of the monitoring device with respect to the tire while experiencing all of these forces while also protecting the monitoring device from damage resulting from these forces.
One method of anchoring the components of the monitoring device as well as the antenna of the monitoring device within a pneumatic tire is to cure these components and antenna within the body of the tire. For instance, the components of the monitoring device and the antenna may be cured within the innerliner of the tire. The components may also be cured within a patch that is then connected to the innerliner. A significant problem with curing these elements in the body of the tire or into a patch is that the battery used to supply power to the components of the monitoring device is damaged or destroyed by the heat of the curing process. The damage to the battery caused by the heat of the curing process has prevented electronic monitoring devices from being embedded within a green tire and then cured into the tire during the green tire cure process. The damage to the battery is especially unfortunate because positioning the antenna and monitoring device components within the innerliner or within a patch that is connected to the innerliner allows the components and antenna to be ideally positioned and secured for use with the tire. It is thus desired in the art to provide an apparatus and method for connecting the monitoring device to the tire by curing the components and antenna of the monitoring device within the tire or a patch that is connected to the tire and then subsequently connecting the battery to the components.